From 1ea998015e5fce3cb14885cfe09ec8ad96a8f203 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bastian=20M=C3=BCller?= <bastian@turbolent.com>
Date: Wed, 12 Nov 2025 15:23:29 -0800
Subject: [PATCH] optimize event emission

only convert arguments, do not transfer (avoid unnecessary copies)
---
 bbq/compiler/compiler.go             | 14 +++++++++-
 bbq/compiler/compiler_test.go        |  2 +-
 interpreter/interpreter_statement.go |  2 +-
 interpreter/misc_test.go             | 38 ++++++++++++++++++++++++++++
 4 files changed, 53 insertions(+), 3 deletions(-)

diff --git a/bbq/compiler/compiler.go b/bbq/compiler/compiler.go
index 596c563cc5..1c55013173 100644
--- a/bbq/compiler/compiler.go
+++ b/bbq/compiler/compiler.go
@@ -1619,7 +1619,19 @@ func (c *Compiler[_, _]) VisitEmitStatement(statement *ast.EmitStatement) (_ str
 			invocationExpression := statement.InvocationExpression
 			arguments := invocationExpression.Arguments
 			invocationTypes := c.DesugaredElaboration.InvocationExpressionTypes(invocationExpression)
-			c.compileArguments(arguments, invocationTypes)
+
+			// Instead of compiling arguments as usual (via compileArguments),
+			// only convert the arguments and don't transfer them.
+
+			for index, argument := range arguments {
+				c.compileExpression(argument.Expression)
+
+				parameterType := invocationTypes.ParameterTypes[index]
+				parameterTypeIndex := c.getOrAddType(parameterType)
+				c.emit(opcode.InstructionConvert{
+					Type: parameterTypeIndex,
+				})
+			}
 
 			argCount := len(arguments)
 			if argCount >= math.MaxUint16 {
diff --git a/bbq/compiler/compiler_test.go b/bbq/compiler/compiler_test.go
index 3ebbd96a1f..e8a3da2efc 100644
--- a/bbq/compiler/compiler_test.go
+++ b/bbq/compiler/compiler_test.go
@@ -1336,7 +1336,7 @@ func TestCompileEmit(t *testing.T) {
 			opcode.InstructionStatement{},
 			// x
 			opcode.InstructionGetLocal{Local: xIndex},
-			opcode.InstructionTransferAndConvert{Type: 1},
+			opcode.InstructionConvert{Type: 1},
 			// emit
 			opcode.InstructionEmitEvent{
 				Type:     2,
diff --git a/interpreter/interpreter_statement.go b/interpreter/interpreter_statement.go
index 66c3c1344c..573470bf7f 100644
--- a/interpreter/interpreter_statement.go
+++ b/interpreter/interpreter_statement.go
@@ -403,7 +403,7 @@ func (interpreter *Interpreter) VisitEmitStatement(statement *ast.EmitStatement)
 			argumentType := argumentTypes[i]
 			parameterType := parameterTypes[i]
 
-			eventFields[i] = TransferAndConvert(
+			eventFields[i] = ConvertAndBoxWithValidation(
 				interpreter,
 				value,
 				argumentType,
diff --git a/interpreter/misc_test.go b/interpreter/misc_test.go
index 7fb33446bc..c1cded3705 100644
--- a/interpreter/misc_test.go
+++ b/interpreter/misc_test.go
@@ -7340,6 +7340,44 @@ func TestInterpretEmitEvent(t *testing.T) {
 	)
 }
 
+func BenchmarkEmit(b *testing.B) {
+
+	inter, err := parseCheckAndPrepareWithOptions(
+		b,
+		`
+          event Foo(ints: [Int])
+
+          fun test() {
+              var i = 0
+              while i < 1000 {
+                  emit Foo(ints: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
+                  i = i + 1
+              }
+          }
+        `,
+		ParseCheckAndInterpretOptions{
+			InterpreterConfig: &interpreter.Config{
+				OnEventEmitted: func(
+					_ interpreter.ValueExportContext,
+					_ *sema.CompositeType,
+					_ []interpreter.Value,
+				) error {
+					return nil
+				},
+			},
+		},
+	)
+	require.NoError(b, err)
+
+	b.ReportAllocs()
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		_, err := inter.Invoke("test")
+		require.NoError(b, err)
+	}
+}
+
 func TestInterpretReferenceEventParameter(t *testing.T) {
 
 	t.Parallel()